This invention relates to underwater pipelines and more particularly to underwater pipeline junction manifolds and means for accurately orienting the manifold to existing pipelines on the ocean floor.
Underwater pipeline junctions manifolds are used in the offshore drilling industry to join pipelines from several wells to a common point. The various pipelines run to the junction manifold from the respective wells arriving at the manifold at different angles. A main pipeline then runs from the junction manifold to onshore facilities or to a deep water port distribution system. The junction manifold is fabricated and constructed with flanges to receive the incoming pipelines at these different angles. When placing the junction manifold on the ocean floor, it is necessary to orient the manifold relative to the incoming pipelines so that the pipelines will line up with the flanges on the manifold.
Heretofore, a number of methods have been used in attempts to install and orient the manifold. This may become increasingly difficult to do accurately in deep water, or when the manifold itself is relatively small, particularly if an acoustic type descent and locating method is used. In the acoustic method, an acoustic transmitter is on the manifold, while another is placed at a known location on the sea floor. Radio signals from the two transmitters are received and displayed on an oscilloscope on board a ship. As the manifold is lowered, the relative position of the two transmitting signals can be measured, since one is coming from a fixed known location. This method, though frequently satisfactory, is not entirely reliable, particularly when the manifold is relatively small and/or when it is being installed in deep water.
Also, it does not satisfactorily provide for confident orientation-direction of the manifold.
Thus, the present invention relates to an apparatus for accurately positioning and orienting an underwater pipeline junction manifold relative to existing underwater pipelines. More particularly, the present invention relates to an apparatus and method for installing a manifold of small size and/or any manifold in relatively deep water of up to one thousand (1,000) feet or more.